<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<script src="../js/vue.js"></script>
<style>
    .hb {
        width: 100px;
        height: 100px;
        background-color: red;
        transition: 2s;
    }

    .hb:hover {
        width: 300px;
    }
</style>

<body>
    <div id="app">
        <h1 :class="hb">{{msg}}</h1>
    </div>
    <script>
        const vm = new Vue({
            el: '#app',
            data: {
                msg: '掰棒子的速度好快！！',
                hb: 'hb'
            },
        })
    </script>
</body>

</html>